Drip Irrigation for Vegetable Production

1 IiDRIP Irrigation FOR Vegetable PRODUCTIONDrip Irrigation for Vegetable ProductionBOOK 7 ContentsIntroduction 1 Making every drop count drivers for water and nutrient efficiency 2 drip Irrigation at a glance 3 drip Irrigation for vegetables 4 Economics of drip Irrigation 6 Grower experiences 7 Growers successfully using drip Irrigation today 7 Growers who have used drip Irrigation but no longer do 8 Growers who are uncertain about drip Irrigation 8 New Zealand case studies 9 Design and installation 15 System specification 15 Design 18 Installation 25 Commissioning 28 Management 29 Maintenance 29 Irrigation scheduling 33 Recovery and disposal of used dripline 35 References 36 This book is part of a series providing a comprehensive training resource for Irrigation industry participants in New introduces drip Irrigation as a viable option for Vegetable Production , giving an overview, descriptions of technologies and an outline of the concepts for successful drip No.

2 978-0-473-27292-0 Compiled by: D. J. Bloomer, P. Johnstone and J. Holland. Irrigation New Zealand 2013 Supported by Sustainable Farming Fund1iDRIP Irrigation FOR Vegetable PRODUCTIONI ntroductionThis booklet introduces drip Irrigation as an option for New Zealand Vegetable growers. Its aims include: presenting an overview of drip Irrigation describing the technologies involved explaining key concepts that support successful drip Irrigation , and highlighting key issues to consider and questions to provides sufficient base information for a grower to decide whether to further investigate the use of drip Irrigation for their Vegetable Production operations.

3 While it has been prepared with Vegetable growers in mind, we anticipate the information will be of interest to growers of arable crops and considering any Irrigation option, soil, crop, climate, farm layout and manager and operator knowledge specific to the farm must be carefully evaluated. This book does not replace the need for specific, specialist advice, or describe specific component options. It makes no attempt to explain the hydraulic design processes required to engineer a drip Irrigation system. That is specialist work, requiring specialist knowledge and experience. 2iDRIP Irrigation FOR Vegetable PRODUCTIONINTRODUCTIONM aking every drop count drivers for water and nutrient efficiencyWATER EFFiCiENCY AND PRODUCTiViTYDrip irrigated plants need as much water as plants irrigated in other ways.

4 The amount needed depends on climate and the crop. Hotter, drier climates drive higher water use, measurable as evapotranspiration (the evaporation loss from the soil and plant surfaces and transpiration through the pores of the plants leaves). If plants do not have sufficient access to readily available water, their growth will slow and ultimately stop. Some plant types require more water than others, and some show a quicker and more severe response to drought. For most crops, the amount of yield lost for each millimetre of drought stress is predictable. There are, however, some cases where moderate drought stress at critical times may enhance yield quantity or quality.

5 No form of Irrigation is 100% water efficient but, of the options, drip Irrigation can be extremely efficient. Very high distribution uniformity, frequent small irrigations, reduced soil surface wetness and applying the right amount very close to plant roots all combine to offer high water use efficiency. But to actually be highly efficient drip , like any Irrigation , requires excellent design, maintenance, management and AND NUTRiENT AND SEDiMENT LOSSI rrigation water is lost from the soil in several different ways: Water that passes through the plant and is lost as transpiration is effectively used. It helps the plant take up nutrients and helps the cool the leaves.

6 Water that runs across the soil surface and exits the target area, is wasted. It may cause harm by washing sediments and nutrients into water ways. It can also cause ponding and crop losses due to saturation. Water removed through drainage is also wasted, and also carries nutrients potentially affecting ground water, rivers and operated drip Irrigation should avoid almost all the wasteful losses, leaving more water available to meet actual crop needs. And by reducing water loss, it reduces nutrient loss as andChemicalInjectionScreenFilterPressure GaugeBack-wash ValveAir ValveBlock Take-off ValvesMain LineLateralFlush ValveFlush ValveBypass ValveSand FilterSand SeparatorHydro-CycloneBack-flowPreventio nDeviceEnd StopPolytube/LateralDripper/EmitterSubma in LinePumpWell/Water SourceFigure 1.

7 Components and layout of a drip Irrigation system. Based on a diagram from Jain Irrigation FOR Vegetable PRODUCTIONDrip Irrigation a glanceDrip Irrigation uses lateral pipes ( driplines ) with fixed emitters laid in parallel rows. Laterals may be laid on the soil surface ( surface drip ) or buried in the ground ( sub-surface drip or buried drip ). Each emitter allows flows of several litres per hour. Their flow rate and spacing along the dripline and the spacing between driplines determines the Irrigation application intensity (mm/h). The depth at which subsurface driplines are installed is selected according to crop, soil type, water source, pests, climate, tillage equipment, and producer preference.

8 Some shallow buried drip Irrigation systems (<20 cm depth) are retrieved and/or replaced seasonally and have many characteristics similar to surface drip Irrigation . Many research reports refer to these shallow systems as surface drip Irrigation (DI) and reserve the term sub-surface drip Irrigation (SDI) for systems intended for multiple-year use that are installed below tillage depthi. Because drip Irrigation emitters have very small outlets (pathways and orifices) and because pressure and flow rates are very low, water quality is extremely important. Sediments, biological growths and chemical residues can all block the outlets and make the system designed and managed drip Irrigation has many advantages over other Irrigation methods, including: elimination of surface runoff high uniformity of water distribution high water usage efficiency flexibility in fertiliser application efficient fertiliser use ability to apply some agrichemicals reduced weed growth reduced plant disease easy automation low labour requirement.

9 Some of the disadvantagesii of drip Irrigation are: establishment cost can be high design and management are quite different to other Irrigation types trained employees are essential maintenance of the dripline system can be time-consuming, especially if buried if the driplines are damaged, the cost and effort to repair them can be large plugging and leakages can cause a high requirement for repairs If using a seasonal/annual system, the extra work involved in laying and retrieving driplines can be significant. 4iDRIP Irrigation FOR Vegetable PRODUCTIONINTRODUCTIONDrip Irrigation for vegetablesiNTERNATiONAL USEDrip Irrigation has been widely adopted throughout the world.

10 The use of sub-surface drip Irrigation in the increased from 163,000 to 260,000 ha in the five-year period from 2003 to 2008, an increase of 59%. In comparison, the surface drip Irrigation land area increased from 566,000 to 694,000 ha, or 23%i. More than 70% of the lettuce produced in the USA is grown in the Salinas Valley. More than half of that acreage is drip BENEFiTSFactors encouraging the use of drip Irrigation in California includeiii: water scarcity caused by periodic droughts and reallocation of existing water supplies for urban and environmental uses, and minimising environmental impacts of agricultural drainage and run-off associated with flood and sprinkler pressures are present in New Zealand.